I'm slowly understanding quantum field theory. I believe I understand non-interacting quantum fields pretty well, I would say as a formalism for real signal analysis, and their relationship to classical random fields, but the mathematics and understanding of interacting quantum fields is harder.

As a manifesto for PhysicsSE, I would say that research in Physics is a cooperative endeavour, in which productive failures are sometimes better for us than apparent successes. Sometimes seeing what is productive takes the ingenuity of many people and many years.